Immatures of Haemagogus aeritinctus are reported from a black mangrove (Avicennia germinans) tree hole on an offshore key in the Belize barrier reef. This is the first report of this species from other than coastal mainland sites in Central America. The high salinity (10,000 ppm) recorded in the tree hole water suggests that this species has a tolerance, or possibly a requirement, for soluble salts that may explain its affiliation solely with mangrove habitats.